(a) Technical Field
The present invention relates to a canister closed valve for an automotive fuel system, more particularly, to a canister closed valve that is positioned at a vent line of a canister, which is exposed to atmospheric air, so as to perform a function of sealing the fuel system.
(b) Description of the Related Art
Generally, in order to comply with fuel system leakage monitoring regulations, in conjunction with On-Board Diagnostics (OBD), a filter tank pressure sensor (FTPS) and a canister closed valve (CCV) are applied to a fuel system.
In particular, in order to perform a function of sealing a fuel system, a canister closed valve (CCV) should be positioned at a pipe channel of a vent line, which is exposed to the atmosphere, and should be mounted behind the vent line and an air filter. Accordingly, the canister closed valve is not directly exposed to the external environment, but communicates with atmospheric air.
A canister closed valve, which is currently applied to vehicles, is a typical solenoid valve, which may include a solenoid (magnetic circuit component) for converting electric energy into magnetic energy and a valve actuating part for converting magnetic energy into kinetic energy so as to open or close a pipe channel.
In such a canister closed valve, when the power is applied to a coil, a core and a plunger are magnetized by a magnetic field, thereby causing a plunger to move up and down. At this point, since the core and the plunger must have sufficient magnetic performance, suitable materials are limited.
FIG. 3 (RELATED ART) is a cross-sectional view showing a conventional canister closed valve for an automotive fuel system.
The canister closed valve includes an upper body 100 for holding a coil assembly and for protecting internal components; a lower body 110 serving as a fluid flow channel; a plunger 120, which is magnetized and moved up and down upon the application of power; a coil assembly for converting electric energy into magnetic energy; a core 140 as a magnetic circuit component, which guides the upward and downward movement of a rod; a rod assembly 150, which is composed of the rod 150a and a seal 150b so as to block the pipe channel by the upward and downward movement of the plunger 120; and a spring 160 for pushing the rod assembly 150 and the plunger 120 so as to open the pipe channel.
Accordingly, during self-diagnosis, power is applied to the coil assembly 130, and the plunger 120 and the rod assembly 150 are lowered, thereby blocking the pipe channel of the lower body 110. Normally, the application of power is shut off, and the rod assembly 150 and the plunger 120 are raised by the restoring force of the spring 160, thereby opening the pipe channel of the lower body 110.
Recently, problems such as frequent lighting of an OBD warning lamp have occurred in certain extremely cold regions. As a result of various investigations, it was determined that malfunctions of the OBD warning lamp were caused by corrosion of the internal components of a canister closed valve, that is, a de-icing agent, which may be excessively dispersed on a road and splashed due to the travel of vehicles, and air containing calcium chloride power that is introduced into the inside of the canister closed valve through a vent line, which is exposed to the atmosphere, in the direction of the arrows in FIG. 3, thereby causing the internal components of the canister closed valve to be corroded.
Although the canister closed valve is not a component that is exposed to the external environment, it includes components that malfunction due to corrosion. Accordingly, for the purposes of reducing costs incurred by addressing claims and mitigating customer dissatisfaction, it is required to assure corrosion resistance of the associated components such that they are capable of a service life of 15 years or 150,000 miles.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.